The invention concerns a flat textile material as will be described further herein.
In respect of permeability, textile materials can be divided into three groups, namely, permeable, impermeable and selectively permeable materials. A fluid is selected in this case as an example of a medium whose passage through a textile material is to be considered. Both textile materials which are permeable to fluid (normal fabric) and textile materials which are impermeable to fluid (fabric with closed pores) have been known for a long time. An example of a textile material which is selectively permeable to fluid is cotton or corresponding mixed fabrics coated with PTFE, known by the brand name of Gore-Tex.
The permeability of known textile materials is dependent on environmental parameters such as temperature and air humidity. This prevents an adjustment of the permeability as a result of a variation of such an environmental parameter. For example, the pore size of a Gore-Tex fabric, which is not dependent on environmental parameters, results in a compromise between the wind-tightness and the water vapour permeability of this material. If the outside temperature is low, however, it is desirable to have a wind-tight textile material, i.e., with more closed pores, whereas if the outside temperature is higher it is desirable to have a more actively breathing textile material which is permeable to water vapour, with larger, more open pores.
The object of the present invention is to develop a textile material according to the the claims in such a way that its permeability is variable in dependence on environmental parameters.
This object is achieved, according to the invention, by a textile material with the features stated in the claims.
The elements which control the permeability of the textile material define openings or pores in the textile material according to the invention whose inside width varies in dependence on environmental parameters. For example, if the environmental parameter is the temperature, then textile materials can be made in such a way that, for example, their permeability increases either with increasing temperature or with decreasing temperature. Permeability which increases with increasing temperature is desired in the case of clothing, for example, particularly in sports and leisure clothing. When the body temperature of the wearer increases, as a result of either the wearer""s own exertion or increasing outside temperature, the enlarging openings can increase the breathing activity of the clothing made from such a textile material. A reduction in the permeability of an item of clothing at increased temperature can be used, for example, for therapeutic purposes.
If the permeability of the textile material in respect of light is considered as a further example, a textile material whose light transmission decreases with increased temperature (or intensified insolation) can be used for beach clothing or sun screens, or also as a textile material which can be used for covering greenhouses.
For certain applications, it can also be advantageous that, starting from a predefined temperature, the permeability of the textile material increases or decreases in the case of both an increase and a decrease in the temperature, relative to the predefined temperature. Such textile materials can be used, for example, as covers for industrial installations. A textile material with a permeability which, starting from a predefined temperature, decreases in the case of both an increase and a decrease in the temperature can, for example, prevent the emergence of vapours or other fluids which develop in the case of a temperature deviation from a predefined process temperature. The reverse effect, in which the permeability of the textile material increases in the case of both a temperature increase and a temperature decrease in relation to a predefined temperature, can be used, for example, as a controllable filter in chemical fractionation.
The use of control element pairs according to the claims permits the attainment of passage openings of defined sizes, resulting in a defined permeability characteristic. Such a textile material is used, for example, if complete impermeability, e.g. water-tightness, is required in the presence of certain environmental parameters, so that all pores or openings can be closed in a defined manner, down to a passage width of zero.
In the case of a textile material according to the claims, use is made of the fact that the control elements, which are of different material, respond differently to one or more environmental parameters. An example of this is the use of control elements made form materials with differing temperature expansion coefficients. Materials with differing swelling behaviour, i.e., differing volume expansion in dependence on the air humidity, for example, can also be used.
The control elements according to the claims are designed in such a way that a variation of environmental parameters likewise produces different effects on the different control element types, which in turn affects the permeability of the material. If the control elements are of differing geometry, the textile material can also be made from a single material only, which simplifies production.
In the case of the embodiment of the textile material according to the claims, use is made of an effect similar to a bimetallic behaviour. The environmental parameter operating range of the textile material can be predefined through the choice of the value of the environmental parameter at which the layers of material dependent on the environmental parameter are jointed together.
In the case of the textile material designed according to the claims, the volume variation of the capsules/micro-capsules can be used for closing passage channels or openings in the textile material. Preferably, in this case a fluid with a high vapour pressure is used for the filing and a material with good elasticity is used for the elastic enclosure. A material with good elasticity in this case is a material which, when sued as an enclosure for a capsule/microcapsule, permits an enlargement of the diameter of such a capsule/micro-capsule by, for example, a factor of 2 for a temperature increase of 100xc2x0 C. The permeability characteristic of the textile material can then be adapted to given requirements, depending on the substances selected for the enclosure and the filing.
Preferably, a textile material according to the claims is used, since, in the temperature range which is relevant to the clothing, the vapour pressure is then highly dependent on the temperature and, consequently, the diameter of the capsule/micro-capsule is varied greatly by the temperature.
A sufficiently secure and cost-effective bond between the capsules/micro-capsules and the fibres is achieved by the design of the textile material according to the claims.
In the case of a textile material according to the claims, the permeability can be varied greatly in dependence on an environmental parameter, since the size and the density of the openings can be varied within wide limits.
The design according to the claims results in a closing force which tends to lay the layers of material against one another and which must be overcome by the capsules/micro-capsules which expand in dependence on an environmental parameter. Such a closing force provides for a reversible control of the permeability of the textile material. In addition, the layers of material are securely joined together.
A preferred embodiment of the textile material is that according to the claims. The recesses provided for the capsules/micro-capsules enable the layer of material to lie on one another in a sealing manner when the capsules/micro-capsules have reduced in size, in dependence on an environmental parameter, in such a way that they lie completely in the recesses.
The design of the textile material according to the claims offers the possibility of producing a basic fabric using a conventional manufacturing method and subsequently inserting the capsules/micro-capsules, which then create the permeability, dependent on environmental parameters, of the textile material. In this case, likewise, depending on the thickness of the textile material used and beyond a certain density and size of the capsules/micro-capsules, on average a virtually complete impermeability is achieved if desired.
The design according to the claims can also result in the permeability being highly dependent on one or more environmental parameters. In this case, likewise, the above-mentioned bimetal effect can be exploited in combination with the fabric tongues.
The design according to the clams enables textile material which is controllably permeable to fluid to be produced relatively cheaply. In this case, the main layer of material, apart from the openings in it, is substantially impermeable to fluid. The control thread can then expand in dependence on, for example, temperature or can swell in dependence on air humidity in order to close the openings.
The control element design according to the claims means that the diameter of the control threads varies greatly in dependence on environmental parameters. A fabric can also be made exclusively from such control threads. The gaps between the control threads are then closed or opened by the variation in their diameter, the permeability of the textile material being varied as a result. Alternatively, it is possible, for example, for such a control thread to be inserted through openings of a main material layer, so that these openings are then opened or closed in dependence on environmental parameters.
In the case of the threads being designed according to the claims, the bimetal effect is again used to deform threads.
The design accordingly to the claims does not exploit any special property of environmental parameter dependence of the lacquer coating, but rather its shielding effect in combination with a behaviour of the threads which is dependent on environmental parameters. A range of other materials is therefore available which impart to a thread a deformation which is dependent on environmental parameters.
The embodiment according to the claims can be produced with conventional weaving technology and another embodiment according to the claims with conventional knitting technology. In the case of known knitting machines, some of the supplied threads, e.g. half, can consist of threads which are dependent on environmental parameters and the remainder of threads made from material which is substantially non-dependent on environmental parameters.
A control element according to the claims has a temperature and humidity-dependent expansion which differs from multifilament threads, while having the same dimension.
A textile material according to the claims is characterized by a good wearing comfort. If only one material is used, this also both simplifies the product of the textile material and reduces the problem of the occurrence of electrostatic charge.
The invention is described more fully below using embodiment examples, with reference to the drawing, wherein: